DRINKS S. Channabasappa, Ed.
Internet-Draft CableLabs
Intended status: Informational May 27, 2009
Expires: November 28, 2009
DRINKS Use cases and Protocol Requirements
draft-ietf-drinks-usecases-requirements-00
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Abstract
This document captures the use cases and associated requirements for
interfaces to provision session establishment data into SIP Service
Provider components that aid with session routing. Specifically, the
current version of this document focuses on the provisioning of one
such element, termed the registry.
Table of Contents
1. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
3. Use Cases and Requirements . . . . . . . . . . . . . . . . . . 10
3.1. Registry Provisioning . . . . . . . . . . . . . . . . . . 10
3.1.1. Use Cases . . . . . . . . . . . . . . . . . . . . . . 10
3.1.2. Requirements . . . . . . . . . . . . . . . . . . . . . 14
3.2. Distribution of data into local data repositories . . . . 17
3.3. Miscellaneous Use Cases . . . . . . . . . . . . . . . . . 17
3.3.1. Indirect Peering to Selected Destinations . . . . . . 17
3.3.2. TBD: RN Destinations . . . . . . . . . . . . . . . . . 17
4. Security Considerations . . . . . . . . . . . . . . . . . . . 18
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 19
6. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 20
7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 21
7.1. Normative References . . . . . . . . . . . . . . . . . . . 21
7.2. Informative References . . . . . . . . . . . . . . . . . . 21
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 22
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1. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119].
This document reuses terms from [RFC3261] (e.g., SIP) and [RFC5486]
(e.g., LUF, LRF). In addition, this document specifies the following
additional terms.
Registry: The authoritative source for provisioned session
establishment data (SED) and related information.
Local Data Repository: The data store component of an addressing
server that provides resolution responses.
Destination Group: A set of public identities that are grouped
together to facilitate session setup and routing.
Public Identity: A generic term that refers to a telephone number
(TN), an email address, or other identity as deemed appropriate,
such as a globally routable URI of a user address (e.g.,
mailto:john.doe@example.net).
Routing Group: a grouping of SED records.
SED Record: A SED Record contains much of the session establishment
data or a 'redirect' to another registry where the session
establishment data can be discovered. SED Records types supported
are NAPTRs, CNAME, DNAME, and NS Records.
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Data Recipient: SP or SSP that receives or consumes SED and related
information.
Data Recipient Group: A group of Data Recipients that receive the
same set (or subset) of SED and related information.
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2. Overview
The SPEERMINT WG specifies Session Establishment Data, or SED, as the
data used to route a call to the next hop associated with the called
domain's ingress point. More specifically, the SED is the set of
parameters that the outgoing signalling path border elements (SBEs)
need to complete the call. See [RFC5486] for more details.
The specification of the format and protocols to configure SED is a
task taken up by the DRINKS WG. The use cases and requirements that
have been proposed in this regard are compiled in this document.
SED is typically created by the terminating SSP and consumed by the
originating SSP. For scalability reasons SED is rarely exchanged
directly between the intended parties. Instead, it is exchanged via
intermediate systems - termed Registries within this document. Such
registries receive SED via provisioning transactions from other SSPs,
and then distribute the received data into Local Data Repositories.
These local data repositories are used for call routing by outgoing
SBEs. This is depicted in Figure 1.
*-------------*
1. Provision SED | |
-----------------------> | Registry |
| |
*-------------*
/ \
/ \
/ \
/ \
/ \
/ \
/ 2.Distribute \
/ SED \
V V
+----------+ +----------+
|Local Data| |Local Data|
|Repository| |Repository|
+----------+ +----------+
Figure 1: General Diagram
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In this version of the document, we primarily address the use cases
and requirements for provisioning registries. Future revisions may
include data distribution. The resulting provisioning protocol can
be used to provision data into a registry, or between registries.
This is depicted in Figure 2.
. . . . . . .
. . . . . . . registry . . . . . . .
. . . . . . . . .
. . .
. . provision .
+-----------+ . +-----------+
| | provision +----------+ provision | |
| SSP 1 |------------>| Registry |<-----------| SSP 2 |
| | +----------+ | |
| +-----+ | /\ | +-----+ |
| | LDR | <-------------------- ------------------>| LDR | |
| +-----+ | distribute distribute | +-----+ |
| | | |
+-----------+ +-----------+
. .
. . . . . . . . . . . . . . . . . . . . . . . .
(provision / distribute)
Where, LDR = Local Data Repository
Figure 2: Functional Overview
The following is a summary of the proposed responsibilities for
Registries and Local Data Repositories:
o Registries are the authoritative source for provisioned session
establishment data (SED) and related information.
o Local Data Repositories are the data store component of an
addressing server that provides resolution responses.
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o Registries are responsible for distributing SED and related
information to the local data repositories.
In addition, this document proposes the following aggregation groups
with regards to SED (certain use cases also illustrate these groups):
o Aggregation of public Identifiers: The initial input "key" to a
SED lookup is a public identifier. Since many public identifiers
will share similar (or identical) destinations, and hence return
similar (or identical) SED, provisioning the same set of SED for
millions of public identifiers is inefficient, especially in cases
where the SED needs to be modified. Therefore, an aggregation
mechanism to "group" public identifiers is proposed. This
aggregation is called a "destination group".
o Aggregation of SSPs: It is expected that SSPs may want to expose
different sets of SED, depending on the receiving SSP. This
exposure may not always be unique, in which case an aggregation
makes it efficient. Such an aggregation is proposed, and termed
"Data Receipient Group".
o Aggregation of SED records: Finally, it is anticipated that a
complete set of routing data will consist of more than just one
SED record. To be able to create and use the same set of SED
records multiple times (without creating duplicates) an
aggregation mechanism at this level is proposed, and called
"routing group".
The above aggregations are illustrated in Figure 3.
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+---------+ +--------------+
| Data | |DATA RECIPIENT|
|Recipient|----------->| GROUP |
+---------+ +------.-------+
^
|
|
+--------------+ +---------+
| ROUTING | ------------->| SED |
| GROUP | | Record |
+--------------+ +---------+
^ ^
| |
| |
+--------------+ |
----->| DESTINATION |<----- |
| | GROUP | | |
| +--------------+ | |
| ^ | |
| | | |
| | | |
| | | |
+---------+ +---------+ +---------+ |
| RN | | TN | | Public |-------
| | | Range | |Identity |
+---------+ +---------+ +---------+
Figure 3: Data Model Diagram
A description of the relationships follows:
- An RN is associated with one or more Destination Groups
- A TN Range object is associated with one or more Destination Group
- A Public Identity is associated with zero or more Destination
Group
- A Public Identity is associated with zero or more SED Records
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- A Destination Group is associated with zero or more Routing
Groups.
- A Routing Group is associated with zero or more SED Records;
NAPTRs and other SED Record Types associated with Routes are not
User or TN specific. For example the user portion of a NAPTR
regex will be "\1".
- An Routing Group is associated with zero or more peering
organizations to control visibility/access privs to that Routing
Group and the Destination Groups they expose.
- A Data Recipient Group is associated with (contains) zero or more
Data Recipients to facilitate the allocation of access privileges
to Routing Groups.
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3. Use Cases and Requirements
This section presents the use cases and associated requirements.
3.1. Registry Provisioning
Registry is the authoritative source for session establishment data
(SED). The registry needs to be provisioned with this data to
perform its function. This data includes: destination groups,
routing groups and data recipient groups. It can also include RNs
and TN Ranges. The following sub-sections illustrate the use cases
and the requirements, respectively.
3.1.1. Use Cases
USE CASE #1 Near-real-time provisioning: The registry is
provisioned with data that is not accompanied by an
effective date or time. In such cases, the registry
will validate the data and make it effective in near
real-time.
USE CASE #2 Non-real-time provisioning: The registry is provisioned
via an asynchronous provisioning process. For
instance, an SSP has commissioned a new registry and
wishes to download a very large number of telephone
numbers. Rather than stream individual entities, one
at a time, the SSP's back-office system prefers to
perform the operation as a set of one or more batches
(e.g., via an external data file), instead of the near-
real-time provisioning interface.
USE CASE #3 Deferred provisioning: The registry is provisioned with
data that is accompanied by an effective date and time.
In scenarios such as this, the registry will validate
the data and wait until the effective date and time to
make it effective. TBD: What happens if near-real time
data overrides data parked for later incorporation?
USE CASE #4 Intra-network SED: SSP wishes to provision their intra-
network Session Establishment Data (SED) such that it
enables current and future network services to identify
and route real-time sessions. For example, in the case
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of VoIP calls it allows one SoftSwitch (calling) to
discover another (called). The SSP provisions IP
addressing information pertaining to each SoftSwitch,
which is provisioned to the registry but only
distributed to a specific local data repository. This
SED may differ from the SED that is distributed to
other local data repositories.
USE CASE #5 Destination Groups: An SSP may wish to control the flow
of traffic into their network (ingress) based on
groupings of Public Identities. Associating each group
of Public Identities with a specific set of ingress
SBEs or points-of-interconnect. The SSP, for example,
sub-divides the country into four regions: North-East,
South-East, Mid-West, and West-Coast. For each region
they establish points-of-interconnect with peers and
provision the associated SED hostnames or IP addresses
of the SBEs used for ingress traffic. Against each
region they provision the served Public Identities into
groups- termed Destination Groups - and associate those
destination groups with the appropriate points of
ingres.
USE CASE #6 Public Identity is taken out of service: A public
identity (or a TN range) is taken out of service
because it is no longer valid. The Registry receives a
delete operation and removes the public identity from
its database. This can also trigger delete operations
to keep the local data repositories up-to-date.
USE CASE #7 Assigning a set of public identities to a different
Destination Group: A set of public identities are
assigned a different Destination Group which
effectively changes their routing information. This
may be due to a network re-arrangement, a Signaling
path Border Element being split into two, or a need to
do maintenance, two carriers merging, or other
considerations. This scenario can also include an
effective date and time.
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USE CASE #8 Moving an SSP from one Data Recipient Group to another:
An SSP would like to re-assign the Destination Groups
it shares with a peer and move the peer SSP from one
Data Recipient Group to another. This results in the
moved peer seeing a new and different set of routing
data.
USE CASE #9 Inter-network SED (Direct and Selective Peering): In
this case the SSP is the actual carrier-of-record; the
entity serving the end-user. The SSP wishes to
communicate different SED data to some of its peers
that wish to route to its destinations. So the SSP has
implemented direct points-of-interconnect with each
peer and therefore would like address-resolution to
result in different answers depending on which peer is
asking.
USE CASE #10 Separation of Responsibility: An SSP's operational
practices can seperate the responsibility of
provisioning the routing information, and the
associated identities, to different entities. For
example, a network engineer can establish a physical
interconnect with a peering SSP's network and provision
the associated domain name, host, and IP addressing
information. Separately, for each new service
subscription, the SSP's back office system provisions
the associated public identities.
USE CASE #11 Global TN Destinations: The SSP wishes to add or remove
one or multiple fully qualified TN destinations in a
single provisioning request.
USE CASE #12 TN Range Destinations: The SSP wishes to add or remove
one or multiple TN Range destinations in a single
provisioning request. TN Ranges support number ranges
that need not be 'blocks'. In other words the TN range
start can be any number and the TN range end can be any
number that is greater than the TN range start.
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USE CASE #13 Non-TN Destinations: An SSP chooses to peer their
messaging service with another SSPs picture/video mail
service. Allowing a user to send and receive pictures
and/or video messages to a mobile user's handset, for
example. The important aspect of this use case is that
it goes beyond simply mapping TNs to IP addresses/
hostnames that describe points-of-interconnect between
peering network SSP's. Rather, for each user the SSP
provisions the subscriber's email address (i.e.
jane.doe@example.com). This mapping allows the mobile
multimedia messaging service center (MMSC) to use the
subscriber email address as the lookup key and route
messages accordingly.
USE CASE #14 Tier 2 Name Server: An SSP maintains a Tier 2 name
server that contains the NAPTR records that constitute
the terminal step in the LUF. The SSP needs to
provision an registry to direct queries for the SSPs
numbers to the Tier 2. Usually queries to the registry
should return NS records, but, in cases where the Tier
2 uses a different domain suffix from that used in the
registry, CNAME and NS records may be employed instead.
USE CASE #15 Peering Offer/Acceptance: An SSP offers to allow
terminations from another SSP by adding that SSP to a
Data Recipient Group it controls. This causes
notification of the offered SSP. An SSP receiving a
peering offer should be able to accept or decline the
offer. If the offer is rejected the Registry should
not provision corresponding SED to the rejecting SSP.
It is expected that this capability will apply mainly
in the transit case where non-authoritative parties (in
the sense of not being the terminating SSP for an
identity) wish to offer the ability to reach the
identity and originating SSPs may wish to restrict the
routes that are provisioned to their local data
repositories.
USE CASE #16 Points of Egress: An SSP has a peering relationship
with a peer, and when sending messages to that peer's
point of interconnection, the originating SSP wishes to
use one or more points of egress. These points of
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egress may vary for an given peer. This capability is
supported by allowing an originating SSP to provision
SED for identities terminating to other SSPs where the
originating SSP is itself the data recipient. The
provisioning SSP may make use of multiple data
recipient identities if it requires different sets of
egress points be used for calls originating from
different parts of its network. Routing from egress
points to ingress points of the terminating SSP may be
accomplished by static routing from the egress points
or by the egress points using data provisioned to the
Registry by the terminating SSP.
3.1.2. Requirements
The following data requirements apply:
DREQ1: The registry provisioning data model MUST support the
following entities: public identities, destination groups,
routing groups and data recipient groups.
DREQ2: The registry provisioning data model MUST support the
grouping and aggregation of public identities within
destination groups.
DREQ3: The registry provisioning data model SHOULD support the
grouping and aggregation of TN Ranges within destination
groups.
DREQ4: The registry provisioning data model SHOULD support the
grouping and aggregation of RNs within destination groups.
The following functional requirements apply:
FREQ1: The registry provisioning interface MUST support the
creation and deletion of: public identities, destination
groups, routing groups and data recipient groups.
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FREQ2: The registry provisioning interface MUST support near-real-
time, non-real-time and deferred provisioning operations.
FREQ3: The registry provisioning interface MUST support the
following types of modifications:
- reassignment of one or more public identities from one
destination group to another;
- reassignment of one data recipient from one destination
group to another;
- association and disassociation of a "Default Routing
Group" with a Data Recipient; and,
- identification of a destination group as a "Primary
Provider" destination group or a "Transit" destination
group.
FREQ4: When an entity with a different client identifier than that
of the carrier of record for a public identity in a
destination group adds a new SSP to a destination recipient
group associated with that destination group, the registry
provisioning interface MUST: a) notify the new SSP of the
updated routing information (which constitutes a peering
offer) b) not provision the SED to the new SSP's LDR unless
the new SSP signals acceptance.
FREQ5: The registry provisioning interface MUST separate the
provisioning of the routing information from the associated
identities.
FREQ6: The registry provisioning protocol MUST define a discrete
set of response codes for each supported protocol operation.
Each response code MUST definitively indicate whether the
operation succeeded or failed. If the operation failed, the
response code MUST indicate the reason for the failure.
FREQ7: The registry provisioning interface MUST allow an SSP to
define multiple sub-identities that can be used in data
recipient groups
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FREQ8: The registry provisioning interface MUST define the
concurrency rules, locking rules, and race conditions that
underlie the implementation of that protocol operation and
that result from the coexistence of protocol operations that
can operate on multiple objects in a single operation and
bulk file operations that may process for an extended period
of time.
FREQ9: The registry provisioning interface MUST support the ability
for a Data Recipient to optionally define a Routing Group as
their Default Routing Group, such that if the Data Recipient
performs a resolution request and the lookup key being
resolved is not found in the Destination Groups visible to
that Data Recipient then the SED Records associated with the
Default Routing Group shall be returned in the resolution
response.
FREQ10: The registry provisioning interface MUST support the ability
for the owner of a Routing Group to optionally define Source
Based Routing Criteria to be associated with their Routing
Group(s). The Source Based Routing Criteria will include
the ability to specify zero or more of the following in
association with a given Routing Group: Resolution Client IP
Address(es) or Domain Names, Calling Party URI(s). The
result will be that the resolution server would evaluate the
characteristics of the Source, compare them against Source
Based Routing Criteria associated with the Routing Groups
visible to that Data Recipient, and return any SED Records
associated with the matching Routing Groups.
FREQ11: The registry provisioning interface MUST track, via a client
identifier, the entity provisioning each data object (e.g.
Destination Group or Routing Group ). This client
identifier will identify the entity that is responsible for
that data object from a protocol interface perspective.
This client identifier SHOULD be tied to the session
authentication credentials that the client uses to connect
into to the registry.
The registry provisioning interface MUST incorporate a data
recipient identifier that identifies the organization
responsible for each data object from a business
perspective. This organization identifier may or may not
ultimately refer to the same organization that the client
Identifier refers to. The separation of the data recipient
identifier from the client identifier will allow for the
separation of the two entities, when the need arises.
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Exactly one client identifier MUST be allowed to provision
objects under a given data recipient identifier. But a
client identifier MUST be allowed to provision objects under
multiple data recipient identifiers.
Objects provisioned under one "Protocol Client Identifier"
MUST NOT be alterable by a provisioning session established
by another "Protocol Client Identifier".
3.2. Distribution of data into local data repositories
This section targets use cases concerned with the distribution of SED
to local data repositories. This is considered out-of-scope for this
version of the document.
3.3. Miscellaneous Use Cases
This section contains additional use cases for consideration.
3.3.1. Indirect Peering to Selected Destinations
The SSP transit provider wishes to provide transit peering points for
a set of destinations. But that set of destinations does not align
with the destination groups that already exist. The SSP wishes to
establish its own destination groups for the destinations that it
provides transit to.
3.3.2. TBD: RN Destinations
The SSP does not wish to provision individual TNs, but instead, for
ease of management, wishes to provision Routing Numbers ((e.g., as in
some number portability implementations). Each RN effectively
represents a set of individual TNs, and that set of TNs is assumed to
change 'automatically' as TNs are ported in and ported out. Note
that this approach requires a query to resolve a TN to an RN prior to
using the provisioned data to route.
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4. Security Considerations
Session establishment data allows for the routing of SIP sesions
within, and between, SIP Service Providers. Access to this data can
compromise the routing of sessions and expose a SIP Service Provider
to attacks such as service hijacking and denial of service. The data
can be compromised by vulnerable functional components and interfaces
identified within the use cases.
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5. IANA Considerations
This document does not register any values in IANA registries.
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6. Acknowledgments
This document is a result of various discussions held by the DRINKS
requirements design team, which is comprised of the following
individuals, in alphabetical order: Deborah A Guyton (Telcordia),
Gregory Schumacher (Sprint), Jean-Francois Mule (CableLabs), Kenneth
Cartwright (Verisign), Manjul Maharishi (Verisign), Penn Pfautz (AT&T
Corp), Ray Bellis (Nominet), the co-chairs (Richard Shockey, Nuestar;
and Alexander Mayrhofer, enum.at GmbH), and the editors of this
document.
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7. References
7.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
7.2. Informative References
[RFC3261] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston,
A., Peterson, J., Sparks, R., Handley, M., and E.
Schooler, "SIP: Session Initiation Protocol", RFC 3261,
June 2002.
[RFC5486] Malas, D. and D. Meyer, "Session Peering for Multimedia
Interconnect (SPEERMINT) Terminology", RFC 5486,
March 2009.
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Author's Address
Sumanth Channabasappa
CableLabs
858 Coal Creek Circle
Louisville, CO 80027
USA
Email: sumanth@cablelabs.com
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